package pers.chao.tool.chars;

import java.io.Serializable;
import java.util.HashMap;
import java.util.TreeMap;

/**
 * Description:
 * 没有注释的方法与{@link String}类似<br/>
 *  <b>注意：</b>没有（数组越界等的）安全检查<br/>
 *  可以作为{@link HashMap}和{@link TreeMap}的key
 *
 * @author W.Chao
 * @date 2020/12/26 15:53
 **/
public class EnhanceChars implements Serializable, CharSequence, Comparable<EnhanceChars>{

	private static final long serialVersionUID = 1L;

	protected final char[] value;

	protected final int offset;

	protected final int length;

	private int hash = 0;

	public EnhanceChars(String str){
		value = str.toCharArray();
		offset = 0;
		length = value.length;
	}

	public EnhanceChars(char[] value, int offset, int length){
		this.value = value;
		this.offset = offset;
		this.length = length;
	}

	/**
	 * 计算该位置后（包含）2个字符的hash值
	 *
	 * @param i 从 0 到 length - 2
	 * @return hash值
	 */
	public int nextTwoCharHash(int i){
		return 31 * value[offset + i] + value[offset + i + 1];
	}

	/**
	 * 计算该位置后（包含）2个字符和为1个int型的值<br/>
	 * int值相同表示2个字符相同
	 *
	 * @param i 从 0 到 length - 2
	 * @return int值
	 */
	public int nextTwoCharMix(int i){
		return (value[offset + i] << 16) | value[offset + i + 1];
	}

	/**
	 * 该位置后（包含）的字符串，是否以某个词（word）开头
	 *
	 * @param i 从 0 到 length - 2
	 * @param word 词
	 * @return 是否？
	 */
	public boolean nextStartsWith(int i, EnhanceChars word){
		// 是否长度超出
		if(word.length > length - i){
			return false;
		}
		// 从尾开始判断
		for(int c =  word.length - 1; c >= 0; c --){
			if(value[offset + i + c] != word.value[word.offset + c]){
				return false;
			}
		}
		return true;
	}

	/**
	 * 填充（替换）
	 *
	 * @param begin 从此位置开始（含）
	 * @param end 到此位置结束（不含）
	 * @param fillWith 以此字符填充（替换）
	 */
	public void fill(int begin, int end, char fillWith){
		for(int i = begin; i < end; i ++){
			value[offset + i] = fillWith;
		}
	}

	public int length(){
		return length;
	}

	public char charAt(int i){
		return value[offset + i];
	}

	public EnhanceChars substring(int begin){
		return new EnhanceChars(value, offset + begin, length - begin);
	}

	public EnhanceChars substring(int begin, int end){
		return new EnhanceChars(value, offset + begin, end - begin);
	}

	@Override
	public CharSequence subSequence(int start, int end) {
		return substring(start, end);
	}

	public String toString(){
		return new String(value, offset, length);
	}

	public int hashCode() {
		int h = hash;
		if (h == 0 && length > 0) {
			for (int i = 0; i < length; i++) {
				h = 31 * h + value[offset + i];
			}
			hash = h;
		}
		return h;
	}

	public boolean equals(Object anObject) {
		if (this == anObject) {
			return true;
		}
		if (anObject instanceof EnhanceChars) {
			EnhanceChars that = (EnhanceChars)anObject;
			if (length == that.length) {
				char[] v1 = this.value;
				char[] v2 = that.value;
				for(int i = 0; i < this.length; i ++){
					if(v1[this.offset + i] != v2[that.offset + i]){
						return false;
					}
				}
				return true;
			}
		}
		return false;
	}

	@Override
	public int compareTo(EnhanceChars that) {
		int len1 = this.length;
		int len2 = that.length;
		int lim = Math.min(len1, len2);
		char[] v1 = this.value;
		char[] v2 = that.value;

		int k = 0;
		while (k < lim) {
			char c1 = v1[this.offset + k];
			char c2 = v2[that.offset + k];
			if (c1 != c2) {
				return c1 - c2;
			}
			k++;
		}
		return len1 - len2;
	}

}
